Since polyolefin-based resins excel in moldability, mechanical properties, electrical properties and the like, they are used in various fields as materials for film forming (forming for film production), sheet forming (forming for sheet production), blow molding, injection molding, and the like. Although polyolefin-based resins generally have excellent physical properties, they are poor in transparency, crystallinity, and rigidity. In order to overcome these problems, technologies have been proposed in which amide compounds and the like are utilized as nucleating agents (Patent Literatures 1 to 5). When polyolefin-based resin compositions containing such amide compounds are molded, molded articles that excel in transparency and mechanical strength can be obtained.
In order to obtain polyolefin molded articles having such excellent properties through commercial production, it is necessary to optimize the molding conditions according to a desired molding method. As the molding methods, various methods are known such as injection molding, extrusion molding, sheet forming, film forming, and blow molding. In injection molding, for example, it is necessary to combine and set various factors such as injection speed, injection pressure, resin temperature (cylinder temperature, nozzle temperature, and the like), resin injection amount, screw rotation speed, mold temperature, mold shape, gate-seal time, and the like. The setting operation is complicated and thus requires effort and time. If such settings are inappropriate, the inappropriateness adversely affects the physical properties of molded articles, or causes white spots or fish eyes due to undissolved matter of a nucleating agent remaining, resulting in defects in the appearance of polyolefin molded articles.